Fill a pot with water and bring to a boil. Heat a wide frying pan or wok over high heat. Add the oil, quickly followed by the pork belly slices and ginger slivers. Sauté until the fat sizzles and there is some minimal browning.

Place the flowering mustard in a mesh strainer with a handle and lower into the pot of boiling water. Cook for about 30 seconds, or until no longer raw. Keep the strainer at the top of the water surface in order to scoop the mustard greens out in one brisk pass. Shake off the hot water and toss into the cooked pork belly. Toss a few minutes more over high heat and season with the salt. Cook for about 30 seconds more, then serve.

Variations: Substitute soy sauce for the salt or chopped ginger for the slivered ginger.